The present invention relates generally to integrated micro-machined and integrated circuit devices. More particularly, the present invention provides a sensing device integral with integrated circuits, such as CMOS integrated circuits, which are foundry compatible. Merely by way of example, the present invention can be applied to a variety of applications, such as consumer, security, industrial, and medical.
Pressure sensors have been widely in industry. Conventional pressure sensors are used in consumer, industrial, and medical applications. Examples of consumer applications include gauges for tires, which are mounted on automobiles. Conventional bathroom type weight scales also use conventional pressure sensing devices. Industrial applications include pressure sensors in pipes for processing chemicals, oil, and semiconductor devices. Medical applications such as blood pressure monitors also rely upon conventional pressure sensing devices. Although highly successful and widely used, conventional pressure sensors have limitations in size, performance, and costs.
Specifically, conventional pressure sensors often use conventional micromachining techniques, common called “MEMS” techniques. Micromachined or MEMS pressure sensors are fabricated using bulk and surface micromachining techniques. Such bulk and surface machining techniques have limitations. That is, conventional bulk and surface machining techniques are often stand alone and are able to produce discrete MEMS based devices. Although highly successful, the MEMS based devices still have limitations. These and other limitations are described throughout the present specification and more particularly below.
Thus, it is desirable to have an improved MEMS device and more particularly pressure sensors.